5G/New Radio (NR) supports periodic and semi-persistent CSI reporting on PUCCH. More specifically, the CSI reports may be carried on PUCCH formats 2 (Short PUCCH), 3, and 4 (Long PUCCH). Various types of CSI reports are supported in NR. The following combinations of channel state information are supported CRI-RI-PMI-CQI, CRI-RI-i1, CRI-RI-i1-CQI, CRI-RI-CQI, CRI, and CRI-RSRP. Additionally, in addition to channel state information, a UE can also be configured to report a L1 RSRP (reference signal received power) report, using a similar mechanism.
Similarly to LTE, NR supports carrier aggregation (CA). Moreover, NR also includes a concept of bandwidth parts (BWP), in which a given carrier may be divided into multiple BW part, and a UE may monitor only such a BW part instead of a full carrier to support UE power saving (multiple BWP per UE), support of UEs with capability smaller than the network carrier (single BWP per UE) and load balancing on a network carrier. The CSI reporting in NR may be either carrier or BW part specific, for example, a CSI report may provide information about one carrier or a BW part but not multiple carriers. However, a UE may be configured to feedback CSI for multiple carriers, such that separate CSI measurement link configuration (MeasLinkConfig) is provided for each one. A MeasLinkConfig links together the resources to be measured (for example, CSI-RS or SSB (Synchronization Signal Block)), the CSI reporting type, and the UL (PUCCH) resources used for reporting the CSI.
Unlike in, for example, LTE, in NR all CSI reports on PUCCH are self-contained, meaning that different parts of a CSI report are all transmitted within the same slot.
Certain abbreviations that may be found in the description and/or in the Figures are herewith defined as follows:
3GPP 3rd Generation Partnership Project
ARI ACK/NACK resource indicator
BW Bandwidth
BWP Bandwidth Part
CC Component Carrier
CG Cell Group
CQI Channel quality indicator
CSI Channel State Information
DCI Downlink Control Information
DL Downlink
gNB 5G Enhanced Node B (Base station)
HARQ-ACK Hybrid Automatic Repeat Request Acknowledgement
L1 (Radio) Layer 1
LTE long term evolution
MME mobility management entity
NCE network control element
NR New radio
NR-PDCCH New radio Physical Downlink Control Channel
N/W Network
Pcell Primary Cell
PMI Precoding Matrix
PRB Physical resource blocks
PScell Primary Scell
PUCCH Physical Uplink Control Channel
Rel Release
RI Rank Indicator
RRC Radio Resource Control
RSRP Reference Signal Received Power
SPS Semi-Persistent Scheduling
SSB Synchronization Signal Block
SR Scheduling Request
UE User Equipment
UL Uplink